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    Default Drug dosing/volume of distribution in obese patients

    Okay, so obese patients have an increased volume of distribution for lipid soluble drugs (narcotics, benzos) so in general they need more for initial plasma concentrations but less maintenance doses d/t decreased clearance, correct? Obese people have more blood volume (not linearly correlated with increase in wt once it gets so high), but a lower total body water percentage? So do water soluble drugs have less of a volume of distribution, so you need less of them? I can't find a good comprehensive list of which drugs are water soluble and which ones are lipid soluble. Does anybody have a good resource for these?

    Nagelhout has a list of drugs and whether to dose them on IBW or TBW. It lists versed, pentothol, propofol, fentanyl, sufentanil, nimbex, and sux to dose at TBW. But then in the paragraph below it says to dose propofol on corrected body weight (IBW+(0.4 x excess weight). ????? I wonder why some are water soluble and some are lipid soluble. You would think you would dose the lipid soluble on TBW and water soluble on IBW. It lists Remifentanil, vec, and roc to dose at IBW.

    We have Nagelhout as our pharmocology teacher and he said that EVERYONE (adults) gets 100 mg of sux...period. So if I have a 135kg person is 135-200mg of sux an acceptable dose? Is this what is commonly seen in practice? It says to dose sux on TBW (total body weight) but that b/c of increased plasma pseudocholinesterase activity the dose needs to be increased. So maybe 1.5mg/kg instead of 1mg/kg of TBW?? How is everyone applying what's in the books into clinical use/application? Thanks everyone!
    Last edited by srna26; 01-26-2011 at 07:25 PM. Reason: additional info added.

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